The invention relates to a system and method for detecting an air leak in an engine.
To meet current emission regulations, automotive vehicles must regulate the air-fuel ratio supplied to the vehicles"" engine cylinders to achieve maximum efficiency of exhaust gas catalysts. For this purpose, it is known to control the air-fuel ratio of an internal combustion engine using an exhaust gas oxygen sensor positioned in the exhaust stream from the engine. The exhaust gas sensor provides feedback data to an electronic controller that calculates desired air-fuel ratio values over time to achieve optimum efficiency of the catalyst in the exhaust system.
When an air leak occurs in an intake manifold of an engine during idle operating conditions, the amount of inducted air is greater than the measured amount of inducted air. Similarly, when an air leak occurs proximate a PCV valve communicating with an intake manifold, the amount of inducted air is also greater than the measured amount of inducted air. Thus, an electronic controller utilizing an inaccurate air measurement may not be able to maintain an optimal air-fuel ratio for optimal catalyst efficiency. Thus, an air leak in the intake manifold or proximate the PCV valve may result in increased emissions and decreased fuel economy. Known engine control systems have been unable to detect air leaks in the intake manifold or air leaks proximate the PCV valve in the engine.
The inventors herein have thus recognized that there is a need for a system and method for detecting an air leak within the engine.
The foregoing problems and disadvantages are overcome by a system and method for detecting an air leak within an engine. The engine includes an intake manifold communicating with an engine cylinder.
The method for detecting an air leak within an engine includes measuring an exhaust gas constituent in exhaust gases from the engine when the engine is operating in an idle operating mode. The method further includes determining whether the air leak is present in the engine based on a level of the measured exhaust gas constituent, a first air-fuel correction value, and a second air-fuel correction value.
A system for detecting an air leak within an engine is also provided. The system includes a first sensor generating a first signal indicative of a mass air flow in the intake manifold. The system further includes a second sensor generating a second signal indicative of an engine speed. The system further includes a third sensor generating a third signal indicative of an air-fuel ratio in exhaust gases from the engine. Finally, the system includes a controller operably connected to the first, second, and third sensors. The controller is configured to determine when the engine is operating in an idle operating mode based on the first and second signals. The controller is further configured to determine whether the air leak is present in the engine based on the third signal, a first air-fuel correction value, and a second air-fuel correction value.
The inventive system and method provides a substantial advantage over known systems and methods. In particular, the system and method can detect when an air leak occurs in the intake manifold or proximate a PCV valve in an engine which known systems are unable to detect.